Examples:
cartography
card
archaeology
archetype
monarchy
legal
loyal
purse
personal
cinema
kinase
car
carpenter
hippopotamus
Mesopotamia
dative
data
date
...
Luxembourgish
donkel
←
German
dunkel
(cognate)
←
Proto-Germanic
*dunkalaz
(inherited)
←
Middle High German
dunkel
(inherited)
←
Old High German
tunkal
(inherited)
←
Dutch
donker
(cognate)
→
Luxembourgish
Donkelheet
(suffix)